Узнать размер tablespacе'ов

set pages 999
col tbs format a20
col Mbytes format 999,999,999
select t.name tbs, ((sum(f.blocks) * t.blocksize) / 1024) / 1024 Mbytes
  from sys.ts$ t, sys.file$ f
 where f.ts# = t.ts#
 group by t.name, t.blocksize
 order by 2 desc
/

Результат:

TBS                      MBYTES
-------------------- ----------
SYSTEM                      300
SYSAUX                      120
EXAMPLE                     100
UNDOTBS1                     25
USERS                         5